CVE-2011-3944 in FFmpeg
Summary
by MITRE
The smacker_decode_header_tree function in libavcodec/smacker.c in FFmpeg before 0.10 allows remote attackers to have an unspecified impact via crafted Smacker data.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2011-3944 resides within the FFmpeg multimedia framework, specifically in the smacker_decode_header_tree function located in libavcodec/smacker.c. This function processes Smacker video files, a proprietary format developed by RAD Game Tools, which FFmpeg supports for decoding purposes. The flaw manifests when the software encounters crafted Smacker data that has been deliberately constructed to exploit the decoding process, potentially leading to arbitrary code execution or system compromise. This vulnerability represents a critical security weakness that affects versions of FFmpeg prior to 0.10, indicating that the issue was present in the software for an extended period without proper mitigation.
The technical nature of this vulnerability stems from inadequate input validation and memory handling within the Smacker file header decoding routine. When FFmpeg processes a malformed Smacker file, the smacker_decode_header_tree function fails to properly validate the structure of the header data, allowing attackers to craft malicious input that can cause unexpected behavior during the decoding process. This type of vulnerability typically falls under CWE-121, which describes stack-based buffer overflow conditions, or CWE-122, which covers heap-based buffer overflow conditions, depending on the specific memory corruption pattern that occurs. The lack of proper bounds checking and input sanitization in the decoding function creates an environment where attacker-controlled data can manipulate the program's execution flow.
The operational impact of CVE-2011-3944 extends beyond simple denial of service scenarios, as it can potentially enable remote code execution on systems that process Smacker media files through FFmpeg. This vulnerability affects a wide range of applications that rely on FFmpeg for multimedia processing, including media players, content management systems, and streaming platforms. Attackers could exploit this weakness by delivering malicious Smacker files through various attack vectors such as email attachments, malicious websites, or compromised media repositories. The vulnerability's remote exploitability means that systems processing user-uploaded content or accessing untrusted media sources could be compromised without user interaction. This aligns with ATT&CK technique T1203, which covers exploitation for execution, particularly in scenarios where multimedia processing components are involved in handling untrusted input.
The remediation strategy for this vulnerability requires immediate upgrading to FFmpeg version 0.10 or later, where the issue has been addressed through improved input validation and memory handling within the smacker_decode_header_tree function. Additionally, system administrators should implement defensive measures such as restricting the processing of untrusted multimedia content, employing sandboxing techniques for media handling components, and monitoring for suspicious file processing activities. Organizations using FFmpeg in production environments should conduct thorough vulnerability assessments to identify systems that may be exposed to this threat, particularly those handling user-generated content or accessing external media sources. The fix implemented in the patched versions typically involves enhanced boundary checking, proper memory allocation validation, and robust input sanitization to prevent the exploitation of the decoding routine. This vulnerability underscores the importance of maintaining up-to-date multimedia processing libraries and implementing proper input validation practices in multimedia applications to prevent similar security issues from arising in the future.